From 945fa0871f03a1db9a9be16e92346d62825decdd Mon Sep 17 00:00:00 2001 From: Matous Hybl Date: Tue, 12 Apr 2022 14:06:53 +0200 Subject: [PATCH] Implement giant (chunked) DMA transfers for DCMI. --- embassy-stm32/src/dcmi.rs | 132 +++++++++++++++++++++++++++ embassy-stm32/src/dma/bdma.rs | 27 +++++- embassy-stm32/src/dma/dma.rs | 164 ++++++++++++++++++++++++++++++++-- embassy-stm32/src/dma/mod.rs | 19 ++++ examples/stm32h7/memory.x | 4 +- 5 files changed, 333 insertions(+), 13 deletions(-) diff --git a/embassy-stm32/src/dcmi.rs b/embassy-stm32/src/dcmi.rs index bf78b631f..b1e557ae1 100644 --- a/embassy-stm32/src/dcmi.rs +++ b/embassy-stm32/src/dcmi.rs @@ -379,7 +379,23 @@ where /// This method starts the capture and finishes when both the dma transfer and DCMI finish the frame transfer. /// The implication is that the input buffer size must be exactly the size of the captured frame. + /// + /// Note that when `buffer.len() > 0xffff` the capture future requires some real-time guarantees to be upheld + /// (must be polled fast enough so the buffers get switched before data is overwritten). + /// It is therefore recommended that it is run on higher priority executor. pub async fn capture(&mut self, buffer: &mut [u32]) -> Result<(), Error> { + if buffer.len() <= 0xffff { + return self.capture_small(buffer).await; + } else { + #[cfg(feature = "unsafe-double-buffered-dma")] + return self.capture_giant(buffer).await; + + #[cfg(not(feature = "unsafe-double-buffered-dma"))] + panic!("For DCMI transfers with length > 0xffff, the `unsafe-double-buffered-dma` must be enabled."); + } + } + + async fn capture_small(&mut self, buffer: &mut [u32]) -> Result<(), Error> { let channel = &mut self.dma; let request = channel.request(); @@ -428,6 +444,122 @@ where result } + + #[cfg(feature = "unsafe-double-buffered-dma")] + async fn capture_giant(&mut self, buffer: &mut [u32]) -> Result<(), Error> { + use crate::dma::TransferOptions; + + let data_len = buffer.len(); + let chunk_estimate = data_len / 0xffff; + + let mut chunks = chunk_estimate + 1; + while data_len % chunks != 0 { + chunks += 1; + } + + let chunk_size = data_len / chunks; + + let mut remaining_chunks = chunks - 2; + + let mut m0ar = buffer.as_mut_ptr(); + let mut m1ar = unsafe { buffer.as_mut_ptr().add(chunk_size) }; + + let channel = &mut self.dma; + let request = channel.request(); + + let r = self.inner.regs(); + let src = r.dr().ptr() as *mut u32; + + unsafe { + channel.start_double_buffered_read( + request, + src, + m0ar, + m1ar, + chunk_size, + TransferOptions::default(), + ); + } + + let mut last_chunk_set_for_transfer = false; + let mut buffer0_last_accessible = false; + let dma_result = poll_fn(|cx| { + channel.set_waker(cx.waker()); + + let buffer0_currently_accessible = unsafe { channel.is_buffer0_accessible() }; + + // check if the accessible buffer changed since last poll + if buffer0_last_accessible == buffer0_currently_accessible { + return Poll::Pending; + } + buffer0_last_accessible = !buffer0_last_accessible; + + if remaining_chunks != 0 { + if remaining_chunks % 2 == 0 && buffer0_currently_accessible { + m0ar = unsafe { m0ar.add(2 * chunk_size) }; + unsafe { channel.set_buffer0(m0ar) } + remaining_chunks -= 1; + } else if !buffer0_currently_accessible { + m1ar = unsafe { m1ar.add(2 * chunk_size) }; + unsafe { channel.set_buffer1(m1ar) }; + remaining_chunks -= 1; + } + } else { + if buffer0_currently_accessible { + unsafe { channel.set_buffer0(buffer.as_mut_ptr()) } + } else { + unsafe { channel.set_buffer1(buffer.as_mut_ptr()) } + } + if last_chunk_set_for_transfer { + channel.request_stop(); + return Poll::Ready(()); + } + last_chunk_set_for_transfer = true; + } + Poll::Pending + }); + + Self::clear_interrupt_flags(); + Self::enable_irqs(); + + let result = poll_fn(|cx| { + STATE.waker.register(cx.waker()); + + let ris = unsafe { crate::pac::DCMI.ris().read() }; + if ris.err_ris() { + unsafe { + crate::pac::DCMI.icr().write(|r| { + r.set_err_isc(true); + }) + }; + Poll::Ready(Err(Error::PeripheralError)) + } else if ris.ovr_ris() { + unsafe { + crate::pac::DCMI.icr().write(|r| { + r.set_ovr_isc(true); + }) + }; + Poll::Ready(Err(Error::Overrun)) + } else if ris.frame_ris() { + unsafe { + crate::pac::DCMI.icr().write(|r| { + r.set_frame_isc(true); + }) + }; + Poll::Ready(Ok(())) + } else { + Poll::Pending + } + }); + + unsafe { Self::toggle(true) }; + + let (_, result) = futures::future::join(dma_result, result).await; + + unsafe { Self::toggle(false) }; + + result + } } mod sealed { diff --git a/embassy-stm32/src/dma/bdma.rs b/embassy-stm32/src/dma/bdma.rs index 30d2a0b97..413285320 100644 --- a/embassy-stm32/src/dma/bdma.rs +++ b/embassy-stm32/src/dma/bdma.rs @@ -76,7 +76,6 @@ foreach_dma_channel! { ); } - unsafe fn start_write_repeated(&mut self, _request: Request, repeated: W, count: usize, reg_addr: *mut W, options: TransferOptions) { let buf = [repeated]; low_level_api::start_transfer( @@ -119,6 +118,30 @@ foreach_dma_channel! { ); } + unsafe fn start_double_buffered_read( + &mut self, + _request: Request, + _reg_addr: *const W, + _buffer0: *mut W, + _buffer1: *mut W, + _buffer_len: usize, + _options: TransferOptions, + ) { + panic!("Unsafe double buffered mode is unavailable on BDMA"); + } + + unsafe fn set_buffer0(&mut self, _buffer: *mut W) { + panic!("Unsafe double buffered mode is unavailable on BDMA"); + } + + unsafe fn set_buffer1(&mut self, _buffer: *mut W) { + panic!("Unsafe double buffered mode is unavailable on BDMA"); + } + + unsafe fn is_buffer0_accessible(&mut self) -> bool { + panic!("Unsafe double buffered mode is unavailable on BDMA"); + } + fn request_stop(&mut self){ unsafe {low_level_api::request_stop(pac::$dma_peri, $channel_num);} } @@ -232,7 +255,7 @@ mod low_level_api { // get a handle on the channel itself let ch = dma.ch(ch as _); // read the remaining transfer count. If this is zero, the transfer completed fully. - ch.ndtr().read().ndt() + ch.ndtr().read().ndt() as u16 } /// Sets the waker for the specified DMA channel diff --git a/embassy-stm32/src/dma/dma.rs b/embassy-stm32/src/dma/dma.rs index 0bce37e48..bc796c541 100644 --- a/embassy-stm32/src/dma/dma.rs +++ b/embassy-stm32/src/dma/dma.rs @@ -41,15 +41,27 @@ impl From for vals::Pfctrl { } } +struct ChannelState { + waker: AtomicWaker, +} + +impl ChannelState { + const fn new() -> Self { + Self { + waker: AtomicWaker::new(), + } + } +} + struct State { - ch_wakers: [AtomicWaker; DMA_CHANNEL_COUNT], + channels: [ChannelState; DMA_CHANNEL_COUNT], } impl State { const fn new() -> Self { - const AW: AtomicWaker = AtomicWaker::new(); + const CH: ChannelState = ChannelState::new(); Self { - ch_wakers: [AW; DMA_CHANNEL_COUNT], + channels: [CH; DMA_CHANNEL_COUNT], } } } @@ -129,6 +141,46 @@ foreach_dma_channel! { ); } + unsafe fn start_double_buffered_read( + &mut self, + request: Request, + reg_addr: *const W, + buffer0: *mut W, + buffer1: *mut W, + buffer_len: usize, + options: TransferOptions, + ) { + low_level_api::start_dbm_transfer( + pac::$dma_peri, + $channel_num, + request, + vals::Dir::PERIPHERALTOMEMORY, + reg_addr as *const u32, + buffer0 as *mut u32, + buffer1 as *mut u32, + buffer_len, + true, + vals::Size::from(W::bits()), + options, + #[cfg(dmamux)] + ::DMAMUX_REGS, + #[cfg(dmamux)] + ::DMAMUX_CH_NUM, + ); + } + + unsafe fn set_buffer0(&mut self, buffer: *mut W) { + low_level_api::set_dbm_buffer0(pac::$dma_peri, $channel_num, buffer as *mut u32); + } + + unsafe fn set_buffer1(&mut self, buffer: *mut W) { + low_level_api::set_dbm_buffer1(pac::$dma_peri, $channel_num, buffer as *mut u32); + } + + unsafe fn is_buffer0_accessible(&mut self) -> bool { + low_level_api::is_buffer0_accessible(pac::$dma_peri, $channel_num) + } + fn request_stop(&mut self) { unsafe {low_level_api::request_stop(pac::$dma_peri, $channel_num);} } @@ -151,7 +203,6 @@ foreach_dma_channel! { } } } - impl crate::dma::Channel for crate::peripherals::$channel_peri { } }; } @@ -212,6 +263,94 @@ mod low_level_api { }); } + pub unsafe fn start_dbm_transfer( + dma: pac::dma::Dma, + channel_number: u8, + request: Request, + dir: vals::Dir, + peri_addr: *const u32, + mem0_addr: *mut u32, + mem1_addr: *mut u32, + mem_len: usize, + incr_mem: bool, + data_size: vals::Size, + options: TransferOptions, + #[cfg(dmamux)] dmamux_regs: pac::dmamux::Dmamux, + #[cfg(dmamux)] dmamux_ch_num: u8, + ) { + #[cfg(dmamux)] + super::super::dmamux::configure_dmamux(dmamux_regs, dmamux_ch_num, request); + + trace!( + "Starting DBM transfer with 0: 0x{:x}, 1: 0x{:x}, len: 0x{:x}", + mem0_addr as u32, + mem1_addr as u32, + mem_len + ); + + // "Preceding reads and writes cannot be moved past subsequent writes." + fence(Ordering::SeqCst); + + reset_status(dma, channel_number); + + let ch = dma.st(channel_number as _); + ch.par().write_value(peri_addr as u32); + ch.m0ar().write_value(mem0_addr as u32); + // configures the second buffer for DBM + ch.m1ar().write_value(mem1_addr as u32); + ch.ndtr().write_value(regs::Ndtr(mem_len as _)); + ch.cr().write(|w| { + w.set_dir(dir); + w.set_msize(data_size); + w.set_psize(data_size); + w.set_pl(vals::Pl::VERYHIGH); + if incr_mem { + w.set_minc(vals::Inc::INCREMENTED); + } else { + w.set_minc(vals::Inc::FIXED); + } + w.set_pinc(vals::Inc::FIXED); + w.set_teie(true); + w.set_tcie(true); + + #[cfg(dma_v1)] + w.set_trbuff(true); + + #[cfg(dma_v2)] + w.set_chsel(request); + + // enable double buffered mode + w.set_dbm(vals::Dbm::ENABLED); + + w.set_pburst(options.pburst.into()); + w.set_mburst(options.mburst.into()); + w.set_pfctrl(options.flow_ctrl.into()); + + w.set_en(true); + }); + } + + pub unsafe fn set_dbm_buffer0(dma: pac::dma::Dma, channel_number: u8, mem_addr: *mut u32) { + // get a handle on the channel itself + let ch = dma.st(channel_number as _); + // change M0AR to the new address + ch.m0ar().write_value(mem_addr as _); + } + + pub unsafe fn set_dbm_buffer1(dma: pac::dma::Dma, channel_number: u8, mem_addr: *mut u32) { + // get a handle on the channel itself + let ch = dma.st(channel_number as _); + // change M1AR to the new address + ch.m1ar().write_value(mem_addr as _); + } + + pub unsafe fn is_buffer0_accessible(dma: pac::dma::Dma, channel_number: u8) -> bool { + // get a handle on the channel itself + let ch = dma.st(channel_number as _); + // check the current target register value + ch.cr().read().ct() == vals::Ct::MEMORY1 + } + /// Stops the DMA channel. pub unsafe fn request_stop(dma: pac::dma::Dma, channel_number: u8) { // get a handle on the channel itself @@ -246,7 +385,7 @@ mod low_level_api { /// Sets the waker for the specified DMA channel pub unsafe fn set_waker(state_number: usize, waker: &Waker) { - STATE.ch_wakers[state_number].register(waker); + STATE.channels[state_number].waker.register(waker); } pub unsafe fn reset_status(dma: pac::dma::Dma, channel_number: u8) { @@ -260,9 +399,9 @@ mod low_level_api { } /// Safety: Must be called with a matching set of parameters for a valid dma channel - pub unsafe fn on_irq_inner(dma: pac::dma::Dma, channel_num: u8, index: u8) { + pub unsafe fn on_irq_inner(dma: pac::dma::Dma, channel_num: u8, state_index: u8) { let channel_num = channel_num as usize; - let index = index as usize; + let state_index = state_index as usize; let cr = dma.st(channel_num).cr(); let isr = dma.isr(channel_num / 4).read(); @@ -273,9 +412,16 @@ mod low_level_api { dma.0 as u32, channel_num ); } + if isr.tcif(channel_num % 4) && cr.read().tcie() { - cr.write(|_| ()); // Disable channel interrupts with the default value. - STATE.ch_wakers[index].wake(); + if cr.read().dbm() == vals::Dbm::DISABLED { + cr.write(|_| ()); // Disable channel with the default value. + } else { + // for double buffered mode, clear TCIF flag but do not stop the transfer + dma.ifcr(channel_num / 4) + .write(|w| w.set_tcif(channel_num % 4, true)); + } + STATE.channels[state_index].waker.wake(); } } } diff --git a/embassy-stm32/src/dma/mod.rs b/embassy-stm32/src/dma/mod.rs index 8e9823772..f96ccbf6e 100644 --- a/embassy-stm32/src/dma/mod.rs +++ b/embassy-stm32/src/dma/mod.rs @@ -76,6 +76,25 @@ pub(crate) mod sealed { options: TransferOptions, ); + /// DMA double-buffered mode is unsafe as UB can happen when the hardware writes to a buffer currently owned by the software + /// more information can be found here: https://github.com/embassy-rs/embassy/issues/702 + /// This feature is now used solely for the purposes of implementing giant DMA transfers required for DCMI + unsafe fn start_double_buffered_read( + &mut self, + request: Request, + reg_addr: *const W, + buffer0: *mut W, + buffer1: *mut W, + buffer_len: usize, + options: TransferOptions, + ); + + unsafe fn set_buffer0(&mut self, buffer: *mut W); + + unsafe fn set_buffer1(&mut self, buffer: *mut W); + + unsafe fn is_buffer0_accessible(&mut self) -> bool; + /// Requests the channel to stop. /// NOTE: The channel does not immediately stop, you have to wait /// for `is_running() = false`. diff --git a/examples/stm32h7/memory.x b/examples/stm32h7/memory.x index c23c397a4..026b14b9b 100644 --- a/examples/stm32h7/memory.x +++ b/examples/stm32h7/memory.x @@ -1,5 +1,5 @@ MEMORY { FLASH : ORIGIN = 0x8000000, LENGTH = 1024K - RAM : ORIGIN = 0x24000000, LENGTH = 128K -} \ No newline at end of file + RAM : ORIGIN = 0x24000000, LENGTH = 384K +}